// Copyright 2012 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "src/assembler-inl.h"
#include "src/deoptimizer.h"
#include "src/macro-assembler.h"
#include "src/objects-inl.h"
#include "src/register-configuration.h"
#include "src/safepoint-table.h"

namespace v8 {
namespace internal {

#define __ masm->

    // This code tries to be close to ia32 code so that any changes can be
    // easily ported.
    void Deoptimizer::GenerateDeoptimizationEntries(MacroAssembler* masm,
        Isolate* isolate,
        DeoptimizeKind deopt_kind)
    {
        NoRootArrayScope no_root_array(masm);

        // Save all general purpose registers before messing with them.
        const int kNumberOfRegisters = Register::kNumRegisters;

        // Everything but pc, lr and ip which will be saved but not restored.
        RegList restored_regs = kJSCallerSaved | kCalleeSaved | ip.bit();

        const int kDoubleRegsSize = kDoubleSize * DwVfpRegister::kNumRegisters;
        const int kFloatRegsSize = kFloatSize * SwVfpRegister::kNumRegisters;

        // Save all allocatable VFP registers before messing with them.
        {
            // We use a run-time check for VFP32DREGS.
            CpuFeatureScope scope(masm, VFP32DREGS,
                CpuFeatureScope::kDontCheckSupported);
            UseScratchRegisterScope temps(masm);
            Register scratch = temps.Acquire();

            // Check CPU flags for number of registers, setting the Z condition flag.
            __ CheckFor32DRegs(scratch);

            // Push registers d0-d15, and possibly d16-d31, on the stack.
            // If d16-d31 are not pushed, decrease the stack pointer instead.
            __ vstm(db_w, sp, d16, d31, ne);
            __ sub(sp, sp, Operand(16 * kDoubleSize), LeaveCC, eq);
            __ vstm(db_w, sp, d0, d15);

            // Push registers s0-s31 on the stack.
            __ vstm(db_w, sp, s0, s31);
        }

        // Push all 16 registers (needed to populate FrameDescription::registers_).
        // TODO(1588) Note that using pc with stm is deprecated, so we should perhaps
        // handle this a bit differently.
        __ stm(db_w, sp, restored_regs | sp.bit() | lr.bit() | pc.bit());

        {
            UseScratchRegisterScope temps(masm);
            Register scratch = temps.Acquire();
            __ mov(scratch, Operand(ExternalReference::Create(IsolateAddressId::kCEntryFPAddress, isolate)));
            __ str(fp, MemOperand(scratch));
        }

        const int kSavedRegistersAreaSize = (kNumberOfRegisters * kPointerSize) + kDoubleRegsSize + kFloatRegsSize;

        // Get the bailout id is passed as r10 by the caller.
        __ mov(r2, r10);

        // Get the address of the location in the code object (r3) (return
        // address for lazy deoptimization) and compute the fp-to-sp delta in
        // register r4.
        __ mov(r3, lr);
        __ add(r4, sp, Operand(kSavedRegistersAreaSize));
        __ sub(r4, fp, r4);

        // Allocate a new deoptimizer object.
        // Pass four arguments in r0 to r3 and fifth argument on stack.
        __ PrepareCallCFunction(6);
        __ mov(r0, Operand(0));
        Label context_check;
        __ ldr(r1, MemOperand(fp, CommonFrameConstants::kContextOrFrameTypeOffset));
        __ JumpIfSmi(r1, &context_check);
        __ ldr(r0, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
        __ bind(&context_check);
        __ mov(r1, Operand(static_cast<int>(deopt_kind)));
        // r2: bailout id already loaded.
        // r3: code address or 0 already loaded.
        __ str(r4, MemOperand(sp, 0 * kPointerSize)); // Fp-to-sp delta.
        __ mov(r5, Operand(ExternalReference::isolate_address(isolate)));
        __ str(r5, MemOperand(sp, 1 * kPointerSize)); // Isolate.
        // Call Deoptimizer::New().
        {
            AllowExternalCallThatCantCauseGC scope(masm);
            __ CallCFunction(ExternalReference::new_deoptimizer_function(), 6);
        }

        // Preserve "deoptimizer" object in register r0 and get the input
        // frame descriptor pointer to r1 (deoptimizer->input_);
        __ ldr(r1, MemOperand(r0, Deoptimizer::input_offset()));

        // Copy core registers into FrameDescription::registers_[kNumRegisters].
        DCHECK_EQ(Register::kNumRegisters, kNumberOfRegisters);
        for (int i = 0; i < kNumberOfRegisters; i++) {
            int offset = (i * kPointerSize) + FrameDescription::registers_offset();
            __ ldr(r2, MemOperand(sp, i * kPointerSize));
            __ str(r2, MemOperand(r1, offset));
        }

        // Copy VFP registers to
        // double_registers_[DoubleRegister::kNumAllocatableRegisters]
        int double_regs_offset = FrameDescription::double_registers_offset();
        const RegisterConfiguration* config = RegisterConfiguration::Default();
        for (int i = 0; i < config->num_allocatable_double_registers(); ++i) {
            int code = config->GetAllocatableDoubleCode(i);
            int dst_offset = code * kDoubleSize + double_regs_offset;
            int src_offset = code * kDoubleSize + kNumberOfRegisters * kPointerSize + kFloatRegsSize;
            __ vldr(d0, sp, src_offset);
            __ vstr(d0, r1, dst_offset);
        }

        // Copy VFP registers to
        // float_registers_[FloatRegister::kNumAllocatableRegisters]
        int float_regs_offset = FrameDescription::float_registers_offset();
        for (int i = 0; i < config->num_allocatable_float_registers(); ++i) {
            int code = config->GetAllocatableFloatCode(i);
            int dst_offset = code * kFloatSize + float_regs_offset;
            int src_offset = code * kFloatSize + kNumberOfRegisters * kPointerSize;
            __ ldr(r2, MemOperand(sp, src_offset));
            __ str(r2, MemOperand(r1, dst_offset));
        }

        // Remove the saved registers from the stack.
        __ add(sp, sp, Operand(kSavedRegistersAreaSize));

        // Compute a pointer to the unwinding limit in register r2; that is
        // the first stack slot not part of the input frame.
        __ ldr(r2, MemOperand(r1, FrameDescription::frame_size_offset()));
        __ add(r2, r2, sp);

        // Unwind the stack down to - but not including - the unwinding
        // limit and copy the contents of the activation frame to the input
        // frame description.
        __ add(r3, r1, Operand(FrameDescription::frame_content_offset()));
        Label pop_loop;
        Label pop_loop_header;
        __ b(&pop_loop_header);
        __ bind(&pop_loop);
        __ pop(r4);
        __ str(r4, MemOperand(r3, 0));
        __ add(r3, r3, Operand(sizeof(uint32_t)));
        __ bind(&pop_loop_header);
        __ cmp(r2, sp);
        __ b(ne, &pop_loop);

        // Compute the output frame in the deoptimizer.
        __ push(r0); // Preserve deoptimizer object across call.
        // r0: deoptimizer object; r1: scratch.
        __ PrepareCallCFunction(1);
        // Call Deoptimizer::ComputeOutputFrames().
        {
            AllowExternalCallThatCantCauseGC scope(masm);
            __ CallCFunction(ExternalReference::compute_output_frames_function(), 1);
        }
        __ pop(r0); // Restore deoptimizer object (class Deoptimizer).

        __ ldr(sp, MemOperand(r0, Deoptimizer::caller_frame_top_offset()));

        // Replace the current (input) frame with the output frames.
        Label outer_push_loop, inner_push_loop,
            outer_loop_header, inner_loop_header;
        // Outer loop state: r4 = current "FrameDescription** output_",
        // r1 = one past the last FrameDescription**.
        __ ldr(r1, MemOperand(r0, Deoptimizer::output_count_offset()));
        __ ldr(r4, MemOperand(r0, Deoptimizer::output_offset())); // r4 is output_.
        __ add(r1, r4, Operand(r1, LSL, 2));
        __ jmp(&outer_loop_header);
        __ bind(&outer_push_loop);
        // Inner loop state: r2 = current FrameDescription*, r3 = loop index.
        __ ldr(r2, MemOperand(r4, 0)); // output_[ix]
        __ ldr(r3, MemOperand(r2, FrameDescription::frame_size_offset()));
        __ jmp(&inner_loop_header);
        __ bind(&inner_push_loop);
        __ sub(r3, r3, Operand(sizeof(uint32_t)));
        __ add(r6, r2, Operand(r3));
        __ ldr(r6, MemOperand(r6, FrameDescription::frame_content_offset()));
        __ push(r6);
        __ bind(&inner_loop_header);
        __ cmp(r3, Operand::Zero());
        __ b(ne, &inner_push_loop); // test for gt?
        __ add(r4, r4, Operand(kPointerSize));
        __ bind(&outer_loop_header);
        __ cmp(r4, r1);
        __ b(lt, &outer_push_loop);

        __ ldr(r1, MemOperand(r0, Deoptimizer::input_offset()));
        for (int i = 0; i < config->num_allocatable_double_registers(); ++i) {
            int code = config->GetAllocatableDoubleCode(i);
            DwVfpRegister reg = DwVfpRegister::from_code(code);
            int src_offset = code * kDoubleSize + double_regs_offset;
            __ vldr(reg, r1, src_offset);
        }

        // Push pc and continuation from the last output frame.
        __ ldr(r6, MemOperand(r2, FrameDescription::pc_offset()));
        __ push(r6);
        __ ldr(r6, MemOperand(r2, FrameDescription::continuation_offset()));
        __ push(r6);

        // Push the registers from the last output frame.
        for (int i = kNumberOfRegisters - 1; i >= 0; i--) {
            int offset = (i * kPointerSize) + FrameDescription::registers_offset();
            __ ldr(r6, MemOperand(r2, offset));
            __ push(r6);
        }

        // Restore the registers from the stack.
        __ ldm(ia_w, sp, restored_regs); // all but pc registers.

        // Remove sp, lr and pc.
        __ Drop(3);
        {
            UseScratchRegisterScope temps(masm);
            Register scratch = temps.Acquire();
            __ pop(scratch); // get continuation, leave pc on stack
            __ pop(lr);
            __ Jump(scratch);
        }
        __ stop("Unreachable.");
    }

    bool Deoptimizer::PadTopOfStackRegister() { return false; }

    void FrameDescription::SetCallerPc(unsigned offset, intptr_t value)
    {
        SetFrameSlot(offset, value);
    }

    void FrameDescription::SetCallerFp(unsigned offset, intptr_t value)
    {
        SetFrameSlot(offset, value);
    }

    void FrameDescription::SetCallerConstantPool(unsigned offset, intptr_t value)
    {
        // No embedded constant pool support.
        UNREACHABLE();
    }

#undef __

} // namespace internal
} // namespace v8
